﻿using Prism.Properties;

namespace Prism.Regions.Behaviors;

/// <summary>
/// Provides a base class for region's behaviors.
/// </summary>
public abstract class RegionBehavior : IRegionBehavior
{
    private IRegion region;

    /// <summary>
    /// Behavior's attached region.
    /// </summary>
    public IRegion Region
    {
        get => region;
        set
        {
            if (IsAttached)
            {
                throw new InvalidOperationException(Resources.RegionBehaviorRegionCannotBeSetAfterAttach);
            }

            region = value;
        }
    }

    /// <summary>
    /// Returns <see langword="true"/> if the behavior is attached to a region, <see langword="false"/> otherwise.
    /// </summary>
    public bool IsAttached { get; private set; }

    /// <summary>
    /// Attaches the behavior to the region.
    /// </summary>
    public void Attach()
    {
        if (region == null)
        {
            throw new InvalidOperationException(Resources.RegionBehaviorAttachCannotBeCallWithNullRegion);
        }

        IsAttached = true;
        OnAttach();
    }

    /// <summary>
    /// Override this method to perform the logic after the behavior has been attached.
    /// </summary>
    protected abstract void OnAttach();
}
